1. Field Of The Invention
The present invention relates to an improved method for cladding a nonaluminum core with aluminum cladding in such fashion that undesired galling of aluminum to the bonding rolls is resisted.
2. Brief Description Of The Prior Art
It has been known to clad a metal rod with another metal so as to obtain certain beneficial properties of the core material combined with the desired characteristics of the cladding material. Economic benefits are obtained through the relatively limited use of the generally more expensive cladding material. See generally, U.S. Pat. Nos. 3,714,701; 4,227,061; and 4,331,283. In known systems, it has been suggested to employ one or two metal cladding strips composed of a first material to permit solid phase bonding of the cladding strip or strips about the circumference of a preheated core member of a second material, which may be steel.
For many uses, the clad product is subsequently reduced in diameter, as by a drawing operation, in order to provide a uniformly clad product of the desired dimensions.
It has also been known to provide an aluminum cladding on a steel core by use of powdered aluminum, aluminum strip or aluminum extrusion in creating the cladding.
One of the problems experienced in connection with aluminum cladding on steel, particularly in connection with the cladding of medium and high carbon steel core materials, has been the galling of aluminum to the bonding rolls. This problem is compounded as a result of the need to (a) provide for effective cleaning of both the steel core rod and the aluminum strip, (b) maintain the surfaces cleaned after such cleaning prior to effecting bonding while preheating both components to an adequate temperature to permit effective bonding and (c) maintain cladding speeds which are commercially acceptable.
There remains, therefore, a very real and substantial need for a process for producing a clean, continuously clad product which is provided with a solid aluminum cladding.